Method for the separation of c6 to c10 alpha olefins from c6 to c10 alpha olefin epoxides by azeotropic and vacuum distillation



United States Patent Pennsylvania No Drawing. Filed Oct. 1, 1968, Ser.No. 764,341 Int. Cl. B01d 3/36, 3/10 US. Cl. 203-55 4 Claims ABSTRACT OFTHE DISCLOSURE C to C alpha olefins are separated from admixture with Cto C alpha olefin epoxides by the steps of azeotropic distillation witha C alcohol azeotropic distillation with the C alcohol and water, vacuumdistillation and azeotropic distillation with a C alcohol.

BACKGROUND OF THE INVENTION Field of the invention This inventionrelates to a method of separating C to C alpha olefins from admixturewith C to C alpha olefin epoxides, i.e. C to C 1,2-epoxyalkanes, by thesteps of azeotropic distillation with a C aliphatic monohydroxy alcoholto remove overhead the C to C alpha olefins, azeotropic distillationwith the C alcohol and water to remove overhead the C alpha olefin,vacuum distillation to remove C and C alpha olefin epoxides and finallyazeotropic distillation with a C aliphatic monohydric alcohol to removeoverhead the C alpha olefin leaving as bottoms the C C and C alphaolefin epoxides.

Prior art No prior art is known which shows the combination of steps ofthis invention for the separation of C to C alpha olefins fromadmixtures with C to C alpha olefin epoxides.

SUMMARY OF THE INVENTION The 1,2-epoxyalkanes having 6 to 10 carbonatoms in the molecule are useful as monomers in the production byconventional methods of a wide variety of polymeric materials, bothhomopolymers and copolymers. These compounds because of the reactivityof the oxirane ring can be used as intermediates in the preparation of avery large number of useful compounds by well known chemical reactions.

One method of preparing these compounds involves cracking parafiin waxto give the alpha olefins. These are separated into broad molecularweight fractions, one such fraction being a fraction having from 6 to 10carbon atoms in the molecules. These alpha olefins are epoxidized by anyof the conventional methods including a recent method wherein an organichydroperoxide is used as the oxidizing agent in the presence of amolybdenum containing catalyst.

When the epoxides are made in this manner the reaction mixture willcontain unreacted alpha-olefins as well as the 1,2epoxyalkanes. Theseare not separable by ordinary distillation. In accordance with theinstant invention a method has been found for separating these compoundsby a combination of azeotropic distillation and vacuum distillation. TheC -C alpha-olefins are distilled overhead as an azeotrope with a 0.;alcohol, for

3,480,519 Patented Nov. 25, 1969 "ice example, tertiary butyl alcohol.The C olefin alone or the C to C olefins can be azeotropically distilledoverhead by the use of a combination of water and C, alcohol. Afterremoving the C to C olefins the C and C 1,2-epoxyalkanes are distilledoverhead by ordinary vacuum distillation. Finally, the C alpha-olefin isdistilled overhead by azeotropic distillation with a C aliphaticmonohydroxy alcohol such as n-amyl alcohol, leaving the C C1,2-epoxyalkanes as a bottoms fraction.

In a specific embodiment of the invention the mixture contains only C 43alpha olefins and 1,2-epoxyalkanes having 6 to 8 carbon atoms. These areseparated by azeotropic distillation with a C aliphatic monohydricalcohol to remove the olefins overhead.

It is an object of this invention therefore to provide a method for theseparation of C -C alpha olefins from C C 1,2-epoxyalkanes by acombination of azeotropic distillations and vacuum distillation.

It is a specific object of this invention to separate C -C alpha olefinsfrom C -C l,2.-epoxyalkanes by azeotropic distillation with a C alcohol.

Other objects of this invention will be apparent from the followingdescription of the preferred embodiments and the claims.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The mixtures which areseparable by the method of this invention are the straight chainterminal olefins, i.e., alpha olefins having from 6 to 10 carbon atomsin the molecule and the epoxides made from such olefins,

i.e., the C to C 1,2-epoxyalkanes. The aliphatic monohydric alcoholswhich are used to separate the C to C alpha olefins from the mixturecontain 4 carbon atoms, the preferred alcohol being tertiary butylalcohol. When the mixture contains only C -C alpha olefins and C -C1,2-epoxyalkanes this is the only step required for separation.

The C alpha olefin does not azeotrope with the C alcohols but willazeotrope with a mixture of the C alcohol and water, forming a ternarymixture. Thus water can be added after the removal of the C to C olefinsor water can be added with the alcohol at the start and an azeotrope ofthe C to C olefins, alcohol and water is removed. It is then necessaryto separate by ordinary vacuum distillation the C and C 1,2-epoxyalkanesfrom the undistilled mixture remaining. The C alpha olefin is thereafterremoved by azeotroping it overhead with a C alcohol preferably n-amylalcohol. The C C and C 1,2-epoxyalkanes are left as a bottoms fraction.

The process can be carried out batchwise in a single still or in asemi-continuous manner by using a succession of stills. For example, thecharge mixture consisting of C to C alpha olefins and C to C1,2-epoxyalkanes is fed to the first distillation tower along withtertiary butyl alcohol and the C -C olefins are taken overhead with thetertiary butyl alcohol at a pressure of, for example, 400 mm. In analternate initial step, the charge together with water and alcohol ischarged to the distillation tower and the C -C olefins are takenoverhead along with the tertiary butyl alcohol and water. If water isnot added initially it must be added after the removal of the C to Colefins to take the C olefin overhead. The tertiary butyl alcohol or thetertiary butyl alcohol and water are removed from the distillate byliquid extraction or extractive distillation in a conventional manner.The bottoms from the first tower is charged to a second tower where theC and C epoxides are taken overhead by ordinary distillation at 50-100mm. pressure. The bottoms from the second tower is mixed with n-amylalcohol and charged to a third tower where the C olefin is takenoverhead as an azeotrope with the n-amyl alcohol at about 100 mm.pressure. The C C and C epoxides are taken as bottoms product from thethird tower and the C alcohol is removed from both overhead and bottomsproducts from the third tower by liquid extraction or extractive Crefers to the 6-carbon alpha olefin, the term C refers to the 7-carbonalpha olefin, and so forth, and the term C refers to the 6-carbon1,2-epoxyalkane, the term C 0 refers to the 7-carbon 1,2-epoxyalkane andso forth. The abbreviation TBA refers to tertiary butylalcodistillation. hol and the term n-C OH refers to n-amyl alcohol.

TABLE I Percent Wt. Cut Wt. (Total Ovhd. Pot Press. N0. g.) 0.). C.) C0:C7 C5 C9 C1 000 C70 C50 090 G100 H2O TBA (315-011 75g. TBA plus g. H1Oadded to pot g. TBA added to pot It is also preferred to carry out theazeotropic distil- The total product is tabulated below: lation atpressures below atmospheric pressure in order TABLE II that thedistillation temperature is kept low enough to Component; Wt, percentavoid decomposition of the epoxides. Pressures of from 0 TBA 28.7 50 to600 mm. are suitable with from 50 mm. to about C 5.5 400 mm. beingpreferable. C 4.2 The example which follows will serve to illustrate theC 4.2 invention in greater detail but it should not be construed 50 C3.9 as limiting the invention solely thereto. C 3.7 C 0 7.3 EXAMPLE I 03.0 A distillation was carried out on 225.2 grams of a mix- 8 ture of Cto C alpha olefins and C and C 1,2-epoxy- 9 alkanes. The total amount oftertiary butyl alcohol uti- 10 lized was 337 grams, the amount of waterwas 47 grams and the amount of n-amyl alcohol was 50 grams. It will beunderstood of course, that the quantities of the alcohols and wateremployed should be sufiicient to provide the necessary azeotrope toremove the olefins as has been described.

Excessive amounts should be avoided for economic reasons. Accordingly,the most desirable amounts will depend upon the amount of olefinsoriginally present in the mixture,

In the table there is shown a typical distillation run utilizing theabove-described quantities of materials. It will be noted that since thequantity of olefins in the mixture was not known it was necessary to addalcohol and water successively to the distillation pot until the desiredoverhead fractions had been obtained. The column employed was a normallaboratory Todd column and a 10:1 reflux ratio was employed. In thetable the composition of the cuts are shown in weight percent. Thesymbol The data show that the tertary butyl alcohol-octene-l azeotropehad a boiling range of 67 C. at 400 mm. pressure and a compositionconsisting of 95.7 weight percent tertiary butyl alcohol and 4.3 weightpercent octene-l. The C olefin did not appear in the overhead untilwater was added to the pot and then was taken overhead as a ternaryazeotrope containing 83.4 weight percent tertiary butyl alcohol, 11.5weight percent water and 5.1 weight percent C olefin. The ternaryazeotrope had a boiling point of C. at 400 mm. pressure. After removalof the C olefin the C and C epoxides were taken overhead by distillationat a pressure of about 50 mm. n-Amyl alcohol was then added to the potand the C olefin was taken overhead as an azeotrope having a boilingpoint of 97 C. at mm. and a compositon of 76.5 weight percent n-amylalcohol, 23.5 weight :percent C olefin. The C C and C epoxides remainedas a bottoms product.

As many possible embodiments can be made of this invention withoutdeparting from the broad scope thereof,

it is to be understood that all matter herein set forth is to beinterpreted as illustrative and not as unduly limiting the invention.

We claim:

1. A method for separating alpha-olefins having from 6 to 10 carbonatoms in the molecule from admixture with 1,2-epoxyalkanes having from 6to 10 carbon atoms in the molecule which comprises the steps ofazeotropically distilling the admixture with a C monohydroxy alcohol toremove overhead the alpha olefins having from 6 to 8 carbon atoms in themolecule, azeotropically distilling the undistilled portion with waterand said O; alcohol to remove overhead the C olefin, vacuum distillingthe undistilled portion to remove overhead the 1,2-epoxyalkanes having 6to 7 carbon atoms in the molecule and azeotropically distilling with analiphatic monohydric alcohol having 5 carbon atoms in the molecule toremove overhead the alpha-olefin having 10 carbon atoms in the molecule,leaving the 1,2-epoxyalkanes having from 8 to 10 carbon atoms in themolecule as the bottoms fraction.

2. The method according to claim 1 wherein the azeotropic distillationis initially carried out with water and the C monohydroxy alcohol, toremove overhead the alpha-olefins having from 6 to 9 carbon atoms in themolecule.

3. The method according to claim 1 wherein the alcohol having 4 carbonatoms in the molecule is tertiary butyl alcohol and the alcohol having 5carbon atoms in the molecule is n-amyl alcohol.

4. The method according to claim 2 wherein the alcohol having 4 carbonatoms in the molecule is tertiary butyl alcohol and the alcohol having 5carbon atoms in the molecule is n-amyl alcohol.

References Cited UNITED STATES PATENTS 8/1966 Leis et al 203--63 12/1966Wolgemuth 260-3485 US. Cl. X.R.

